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ssanzone 22-04-2013 11:10

Epoxy vs Fiberglass
 
is there any reason to not use fiber resin instead of epoxy?

i mean... when laying up cloth, it is pretty straight forward as that is that fiber resin is designed for but what about when tabbing in bulkheads or mixing with silica (fiberglass powder) or repairing decks or bulkheads?

at about $150 for 105 and 205 (206 / 209) i could reduce my material costs by 60% for the glass work.

i am 'that guy' who thinks all wood needs to be treated. everything has a layer of fiberglass or a coat of epoxy and is painted before whatever the finish treatment is applied (sole, head liner, mahogany etc).

thoughts?

-steve

neilpride 22-04-2013 11:25

Re: epoxy vs fiberglass
 
For weeting out cloth will be fine , polyester is very thin and wet out cloth nice, for tabbing bulkheads i prefer epoxy, have better adesive properties and is stronger, almost all the repairs this days are made with epoxy , if you found West expensive for your budget try to found cheaper epoxy, here in the island i can get 1 gallon of epoxy + reactor for 45 $ , and is the same stuff as West system , no big diference, same for Microballons , Silica, etc.,Cheers.

motion30 22-04-2013 11:25

Re: epoxy vs fiberglass
 
Steve. when you say fiberglass are you referring to the standard polyester resin ? fiberglass is the actual cloth , the resin is different polyester is the cheapest vinyl ester is a nice step up
an epoxy . most expensive if cost is your concern and strong secondary bonds are required vinyl ester maybe a good choice

roverhi 22-04-2013 11:27

Re: epoxy vs fiberglass
 
Polyester resin does not bond to cured Polyester resin all that well. Have ripped tabbing off the hull with relatively ease when doing modifications. It also doesn't bond all that well to other materials. Polyester resin is also not water proof. The newer resins are much better at resisting water intrusion and the delamination that results. It works fine for 'hot' laminating for hull and deck layups.

Epoxy is just an all around better material for bonding things together. It is also virtually water proof so doesn't have water intrusion issues.

I've quit using polyester resin entirely. Epoxy is just so much better for bonding things together.

ssanzone 22-04-2013 16:06

Re: epoxy vs fiberglass
 
the waterproof bit is the only reason i need to just spend the extra $$ and keep using epoxy.

thanks for the input.

-s

Sam Plan B 22-04-2013 16:31

Re: epoxy vs fiberglass
 
Epoxy resin does not work well with matt. Matt is held together with a binder that is soluable in polyester resin. So, it will not form well in epoxt resin. Also, you have to protect epoxy resin from sunlight because the U.V. will break it down. No type of resin will form a chemical bond after a cure of 48 hours. You have to abrade the existing surface before applying the new lay up. The two surfaces will have a mechanical bond only. Normally that is strong enough.

Epoxy resin is easier to manage beause it can have a longer pot life if you use a "slow" hardener. It is not so sensitive to ambient temperature. It is about 50% more expensive than polyester. Other than that, they both are worked about the same.

CharlieCobra 22-04-2013 20:27

Re: epoxy vs fiberglass
 
Unless ya get Mat bound with epoxy resin, which while a bit more expensive is available. Keep in mind that Gelcoat will NOT stick to epoxy.

motion30 22-04-2013 21:31

Re: epoxy vs fiberglass
 
I have read that gelcoat does not adhere to epoxy. why that is I do not understand I have done small repairs spring gelcoat over epoxy with no issues what are the technical aspects of this?

delmarrey 22-04-2013 22:34

Re: epoxy vs fiberglass
 
Quote:

Originally Posted by Sam Plan B (Post 1217165)
Epoxy resin does not work well with matt. Matt is held together with a binder that is soluable in polyester resin. So, it will not form well in epoxt resin. Also, you have to protect epoxy resin from sunlight because the U.V. will break it down. No type of resin will form a chemical bond after a cure of 48 hours. You have to abrade the existing surface before applying the new lay up. The two surfaces will have a mechanical bond only. Normally that is strong enough.

Epoxy resin is easier to manage beause it can have a longer pot life if you use a "slow" hardener. It is not so sensitive to ambient temperature. It is about 50% more expensive than polyester. Other than that, they both are worked about the same.

An old indian trick I learned is to thin out the epoxy just a little with MEK. It'll soak right into the matt fairly well. It just takes a little longer to cure.

Also the same with the first layer on wood. It helps it to bond to the wood much better, in my experience.

s/v Jedi 22-04-2013 23:04

With epoxy, don't use matt, replace it with cloth. So you alternate woven roving with cloth for epoxy,while you alternate woven roving with matt for polyester and vinylester. Cloth is much stronger than matt, so you can recalculate the layup schedule resulting in a thinner, lighter laminate with epoxy.

The cellulose that binds matt falls apart immediately with epoxy, resulting in a mess. Also, matt does not add much strength to a laminate other than filler and to reduce print-through of the roving.

cal40john 23-04-2013 00:40

Re: epoxy vs fiberglass
 
West Systems thinks you can put gel coat or polyester resin over epoxy


WEST SYSTEM | Projects | Fiberglass Boat Repair and Restoration - Polyester over epoxy

https://www.westsystem.com/ss/assets/...2Polyester.pdf

They also say you can use mat, but the styrene binder does not dissolve so it is less flexible.

WEST SYSTEM - Projects - Chopped stand mat & epoxy

elhix 23-04-2013 02:58

Re: epoxy vs fiberglass
 
Having a lot of prior experience with polyester I mostly used it to build my boat and consequently saved myself several thousand dollarpounds and - I firmly believe - ended up with a very strong, light and watertight vessel.

In some ways polyester is a more forgiving material than epoxy and despite what a lot of people say is more than up to the task if you use a high-quality resin. I used epoxy for certain structural elements and for my rudders and daggerboard - applications where the superior mechanical qualities of epoxy were of benefit. My hulls are polyester with several coats of epoxy high-build coat to achieve the 'waterproof' aspect everybody likes.

Both resins have their idiosyncrasies and it's possible to screw up invisibly with either (the previous poster who ripped tabbing of his hull hadn't found evidence of bad resin, he'd found evidence of bad building). Polyester needs a good key if laminating to a cured surface; epoxy needs to be mixed VERY well and the components measured accurately, plus it also needs a good key. With many epoxies a waxy residue forms on the surface during curing - if you don't THOROUGHLY clean this off you might as well be laminating with jam.

goboatingnow 23-04-2013 04:31

Re: epoxy vs fiberglass
 
I would agree, polyester is very forgiving compared to epoxy. Easier to mix, less fussy about accurate amounts. Lack of pot life control can be an issue in warm temps.

Less chance of being sensitised in my experience too.
dave

sailvayu 23-04-2013 06:14

Re: Epoxy vs Fiberglass
 
WEST has done a great job of convincing amateur boat repairers it is the best thing to use. The truth is it is not.WEST stands for Wood Epoxy Saturation Technique. It was developed for use with wood not fiberglass. Great marketing has made it very popular for a lot of repairs it is not really well suited for.
Let's look at some of the myths
Secondary bonding with Polyester is poor. This is not true and good prep no matter what you use is important. If properly prepared poly will bond just as good as epoxy. Epoxy is more water resistant, yes but most repairs are above the water line so this is irrelevant
WEST claims poly gel coat will bond to epoxy but if you read their test data it is highly biased and not a long term study. And look who wrote it. I might be included to believe an independent study.
Things to consider:
When using Fiberglass the binder for all weaves must be of the type for epoxy not poly. Special material is used with epoxy
Epoxy has poor UV resistance. This is important when making exterior repairs.
Personally I see little need to ever use WEST epoxy when making repairs on a Poly fiberglass boat. It makes little sense as the cost is high and in 99% of repairs the slightly extra strength is irreverent. It makes more sense to use the same material the boat is built with. You would not patch a steel boat with Titanium would you just because it is a bit stronger? Few professionals use WEST to repair boats so why should the owner want to do this? Because WEST has done a great job selling their product.
Yes I use WEST all the time but mostly when working with wood. Below the waterline I use vinyl-ester because in my mind it is more compatible with polyester. I will not argue epoxy is stronger or has better water resistance (NOT water PROOF) but in 99% of repairs I see no reason to use epoxy and several reasons not to use it.

s/v Jedi 23-04-2013 06:51

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by sailvayu (Post 1217578)
Myth: Secondary bonding with Polyester is poor. This is not true and good prep no matter what you use is important. If properly prepared poly will bond just as good as epoxy.
[...]
I will not argue epoxy is stronger

So, does epoxy provide better bonding than polyester or not? I think epoxy shear strength is about 4 times that of vinylester (2,000 psi vs 500 psi) and that vinylester gets it's better properties because it has epoxy molecules mixed in.

I think the only negative to epoxy is it's price.

Here's a good read on it (from professionals): EPOXYWORKS

sailvayu 23-04-2013 07:04

Re: Epoxy vs Fiberglass
 
Once again your source is provided by the same company selling the stuff* (more great marketing) Yes I will not argue epoxy is stronger I am saying this extra strength is not as important in most repairs as some seem to think. And ultimate shear strength is not the same as secondary bonding strength which in my mind is more a result of properly preparation as is it material strength. (methacrylate being and exception)

Sorry I was once an Epoxy zealot myself but have come to the conclusion over 30 years of using the stuff it is not really better most of the time. So I do not agree the only negative is price. As I said there are other reasons.

*Epoxyworks 22 / Winter 2004

Copyright 2003, Gougeon Brothers, Inc. All rights reserved.
This page is maintained by Gougeon Brothers, Inc. Last modified on (11/05/03).
Reproduction in any form, in whole or in part, is expressly forbidden without the consent of the publisher. EPOXYWORKS, Gougeon Brothers, WEST SYSTEM, Episize, Scarffer and Microlight as used throughout this publication, are trademarks of Gougeon Brothers, Inc., Bay City, Michigan, USA.

foggysail 23-04-2013 07:09

Re: Epoxy vs Fiberglass
 
Very informative thread! Question--- where does Bondo fit in? Is it an epoxy?

Thanks-

sailvayu 23-04-2013 07:14

Re: Epoxy vs Fiberglass
 
Bondo is a low quality polyester filler. there are better fillers and I will usually use a vinyl-ester filler. The problem with Bondo is the solids used are not very moisture resistant and regardless of the filler binder (the resin) if the solids are not moisture resistant the filler will be poor

minaret 23-04-2013 07:22

Re: Epoxy vs Fiberglass
 
Are we really having this conversation yet again?


Poly is just fine for 99% of boat stuff. The binder in matt is starch, which is instantly dissolved by epoxy, turning into a sticky goo that's impossible to work with. Thinning your resin or anything else will not prevent this, only going to a different more expensive, hard to find binder will do that. I've been trying for some years now to convince people on this forum that the cult of epoxy is leading them astray. It's just so much more time consuming and expensive, in many cases the cons outweigh the pros. I have used thousands of gallons of both resin systems, for repair and new construction.

sailvayu 23-04-2013 07:26

Re: Epoxy vs Fiberglass
 
Wow someone who has not been sold the bill of goods by the Gougeon Brothers!

foggysail 23-04-2013 07:27

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by sailvayu (Post 1217655)
Bondo is a low quality polyester filler. there are better fillers and I will usually use a vinyl-ester filler. The problem with Bondo is the solids used are not very moisture resistant and regardless of the filler binder (the resin) if the solids are not moisture resistant the filler will be poor


Thanks for quickly explaining my question :thumb:

CharlieCobra 23-04-2013 07:52

Re: Epoxy vs Fiberglass
 
We don't use West Systems very often. We use an epoxy that has a 2:1 mix ratio and contains UV inhibitors. We've used mat with this epoxy just fine.

s/v Jedi 23-04-2013 08:01

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by sailvayu (Post 1217640)
Yes I will not argue epoxy is stronger I am saying this extra strength is not as important in most repairs as some seem to think.

Agreed. And also that a polyester hull repair with epoxy gives a hard spot while a repair with the same materials provides a better (never perfect, will always be a hard spot) match.

West System is of course the manufacturer. But their lab tests are not fake like you seem to believe. There are plenty who found similar results. The document I linked showed a typical repair with 12:1 bevel where polyester restored 70% of original strength and epoxy showed 80% of original strength. I don't think you dispute that, I think you just say so because of the principle that it is the manufacturer stating it.

@all about matt: starch and cellulose are basically the same. The important thing is that epoxy immediately breaks it down while polyester gives you enough time to work with it. For once Minaret and I agree while using just slightly different words :)

minaret 23-04-2013 08:11

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by CharlieCobra (Post 1217718)
We don't use West Systems very often. We use an epoxy that has a 2:1 mix ratio and contains UV inhibitors. We've used mat with this epoxy just fine.




Matt by itself, or Matt sandwiched between layers of roving or in the form of stitch Matt? I doubt you've successfully done a Matt only layup with regular starch binder and epoxy.

sailvayu 23-04-2013 08:17

Re: Epoxy vs Fiberglass
 
Jedi yes I am a bit jaded by the endless "facts" reported by WEST. and I am sure there is some bias in their reports. The problem with almost all studies of this type is they by nature have to be controlled and and likewise most average boat repairs are equally UN controlled. I tend to go by real world results I see in the field. I am not dead set against epoxy per say but given a choice in most repairs I see not advantage and a few real dis advantages to it. For the armature whom I feel we are all trying to help on these forums I just like to offer an alternative and the reasons for that opinion. let the reader decide based on the information provided. But you have to admit the Gougeon Brothers have done a great job of conniving folks their goop is the best. So I prefer information from sources with no economic gain involved.

s/v Jedi 23-04-2013 09:05

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by sailvayu (Post 1217763)
you have to admit the Gougeon Brothers have done a great job of conniving folks their goop is the best. So I prefer information from sources with no economic gain involved.

They do so good because they came with their complete system for building wood-epoxy boat... which are great boats.

In Europe, MAS epoxy is very popular and it is also widely available in the US. It is as good but they lack the complete all-you-ever-need catalog of West System. That catalog also makes it easy for general, non-specialized retailers like chandleries: no need to go and select fiberglass tapes/cloth etc. as it is all in the catalog.

I still think the little repair kits from West System are pretty neat, deliver good results when following instructions, and are very expensive for what you get. Despite the price, they are very popular.

Where are the polyester repair kits in the chandleries? But you can get them at the NAPA :D

ssanzone 23-04-2013 09:06

Re: Epoxy vs Fiberglass
 
i have a follow up question...

if poly resin does not adhere well to cured poly, how does one layer (i am planning mat (2x) under cloth).

do i need to apply the next layer while the previous layer is still setting up?

i have never entertained this notion as i have, to date, always used expoxy.

other question, i want to lay up cloth on the new wood bulkheads and figured i would use poly and light cloth because of the volume. should i be using WEST as i am adhering cloth to wood?

-steve

sailvayu 23-04-2013 09:31

Re: Epoxy vs Fiberglass
 
Jedi yes I agree and WEST as a company is a very good one. they have a good product and provide great information on how to use it. they are a good example of a well run company that took a vanilla product and made it look like gold. And yes their wood epoxy boats are very nice. I just get worked up with the "it is the only thing to use" attitude you get with a lot of boat owners.

ssanzone, Poly DOES adhere well to Poly this is one of the biggest myths going. Proper preparation is key but the applies to almost any resin used. I have done some repairs and years later had to change things (like 20 years) and not been able to break the bond (ended up grinding it off) This secondary bonding thing comes from those repairs poorly made and I have seen as much epoxy peel off as poly with a poor job.

For your bulkhead repair I personally would use poly or vinyl-easter but I would put as much effort into good prep. In that application If you use epoxy I would wet the wood down with epoxy and let it set other wise the wood will wick the resin out of the material. use Epiglass not regular fiberglass as has been mentioned because of the binder problems. Use a layer of CMS (chopped strand mat) first then a couple layers of 1808 or the like over that. Use a fast cure resin as most epoxies do not have a great thixotrope and will run out of the material (another advantage to poly) on vertical surfaces. Mix small batches and work fast. would help to have some assistance. Like I say I personally would use polyester but epoxy in this application is fine.

Searanger50 23-04-2013 10:32

Re: Epoxy vs Fiberglass
 
So - to put the fox amongst the the chickens - which is best to repair the holes left in the hull when disused through hulls are removed?

Kevin.

s/v Jedi 23-04-2013 10:36

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by sailvayu (Post 1217867)
Jedi yes I agree and WEST as a company is a very good one. they have a good product and provide great information on how to use it. they are a good example of a well run company that took a vanilla product and made it look like gold. And yes their wood epoxy boats are very nice. I just get worked up with the "it is the only thing to use" attitude you get with a lot of boat owners.

ssanzone, Poly DOES adhere well to Poly this is one of the biggest myths going. Proper preparation is key but the applies to almost any resin used. I have done some repairs and years later had to change things (like 20 years) and not been able to break the bond (ended up grinding it off) This secondary bonding thing comes from those repairs poorly made and I have seen as much epoxy peel off as poly with a poor job.

For your bulkhead repair I personally would use poly or vinyl-easter but I would put as much effort into good prep. In that application If you use epoxy I would wet the wood down with epoxy and let it set other wise the wood will wick the resin out of the material. use Epiglass not regular fiberglass as has been mentioned because of the binder problems. Use a layer of CMS (chopped strand mat) first then a couple layers of 1808 or the like over that. Use a fast cure resin as most epoxies do not have a great thixotrope and will run out of the material (another advantage to poly) on vertical surfaces. Mix small batches and work fast. would help to have some assistance. Like I say I personally would use polyester but epoxy in this application is fine.

If using epoxy, replace matt with cloth or with a stitched matt. For polyester use the standard cellulose binder matt :thumb:

minaret 23-04-2013 11:01

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by Searanger50 (Post 1217949)
So - to put the fox amongst the the chickens - which is best to repair the holes left in the hull when disused through hulls are removed?

Kevin.



Poly. Repair like with like. I would, however, use epoxy for the aforementioned cloth to wood layup, with a good split coat.i

sailvayu 23-04-2013 13:02

Re: Epoxy vs Fiberglass
 
minaret yes I agree but still I would use poly for the bulkhead myself.

jedi I do not agree with cloth for the first layer, mat is used as it lays down and fills voids for a better surface fill and gives more surface area for the following layers to attach to if all done wet. Cloth and fabric tend to bridge small gaps and do not lay against the base material as well this can lead to bond failure. No matter the type of resin a layer of csm followed by what ever weave you are using will always work better. That is the purpose of csm in most laminates to fill voids in the weaves that is why it is used between layers of heavier knits as well. You remember the old mat woving mat woving... now in most knits it is part of the material to save time.

minaret 23-04-2013 13:19

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by sailvayu (Post 1218165)
minaret yes I agree but still I would use poly for the bulkhead myself.

jedi I do not agree with cloth for the first layer, mat is used as it lays down and fills voids for a better surface fill and gives more surface area for the following layers to attach to if all done wet. Cloth and fabric tend to bridge small gaps and do not lay against the base material as well this can lead to bond failure. No matter the type of resin a layer of csm followed by what ever weave you are using will always work better. That is the purpose of csm in most laminates to fill voids in the weaves that is why it is used between layers of heavier knits as well. You remember the old mat woving mat woving... now in most knits it is part of the material to save time.


Agreed. This is basic laminating 101.

s/v Jedi 23-04-2013 13:24

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by sailvayu (Post 1218165)
minaret yes I agree but still I would use poly for the bulkhead myself.

jedi I do not agree with cloth for the first layer, mat is used as it lays down and fills voids for a better surface fill and gives more surface area for the following layers to attach to if all done wet. Cloth and fabric tend to bridge small gaps and do not lay against the base material as well this can lead to bond failure. No matter the type of resin a layer of csm followed by what ever weave you are using will always work better. That is the purpose of csm in most laminates to fill voids in the weaves that is why it is used between layers of heavier knits as well. You remember the old mat woving mat woving... now in most knits it is part of the material to save time.

You can get cloth to follow voids, ridges etc. but it does not fill them: with epoxy, you have to fill them before applying fabrics, which is what I normally do.

You can use matt but with epoxy it needs to be the stitched matt because the cellulose will fall apart the moment it touches epoxy.
The combinations of matt with woven roving are stitched I believe so they would work with epoxy.

I recently used some matt with epoxy because I couldn't get anything else and it was pretty difficult; you end up with just a ball of fibers with epoxy in your hands. I only needed to stuff it into a void, which was doable, but I could not have put it down as a layer.
There is stitched matt; it is made for use with epoxy and solve the issue. I first do faring and fillets, then start with cloth, roving, cloth. Never had to make anything thicker/stronger than that :thumb:

I used matt, roving, matt with polyester once. I did the layup of the piece on a table with all three layers, wet it out and then put the whole thing in place followed by a plastic foil and piece of plywood screwed in place at each side. That worked pretty well. This was to close the cutout of an escape hatch on a cat, so vertical. It would have been impossible with epoxy and the same fiber layup.

Exile 23-04-2013 13:29

Re: Epoxy vs Fiberglass
 
So if poly is preferred for the reasons cited -- most notably in the case of gelcoat deck repairs where epoxy may make it difficult for new gelcoat to adhere -- can anyone recommend a high-quality poly brand/system that is practical for both small jobs & stowage onboard?

I believe poly & vinylester fairing materials have been recommended by Minaret & others in other threads, but I'm not sure I caught any suggestions for resin & catalyst. Obviously, the quantities pros like Minaret use would not be realistic unless smaller containers are available.

s/v Jedi 23-04-2013 13:35

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by Exile (Post 1218193)
So if poly is preferred for the reasons cited -- most notably in the case of gelcoat deck repairs where epoxy may make it difficult for new gelcoat to adhere -- can anyone recommend a high-quality poly brand/system that is practical for both small jobs & stowage onboard?

I believe poly & vinylester fairing materials have been recommended by Minaret & others in other threads, but I'm not sure I caught any suggestions for resin & catalyst. Obviously, the quantities pros like Minaret use would not be realistic unless smaller containers are available.

Here you go: $24 for a quart incl. hardener: TotalBoat Polyester Laminating Resin

:thumb:

TeddyDiver 23-04-2013 13:36

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by sailvayu (Post 1217867)
For your bulkhead repair I personally would use poly or vinyl-easter but I would put as much effort into good prep. In that application If you use epoxy I would wet the wood down with epoxy and let it set other wise the wood will wick the resin out of the material. use Epiglass not regular fiberglass as has been mentioned because of the binder problems. Use a layer of CMS (chopped strand mat) first then a couple layers of 1808 or the like over that. Use a fast cure resin as most epoxies do not have a great thixotrope and will run out of the material (another advantage to poly) on vertical surfaces. Mix small batches and work fast. would help to have some assistance. Like I say I personally would use polyester but epoxy in this application is fine.

:banghead: Reader be aware!

roverhi 23-04-2013 15:03

Re: Epoxy vs Fiberglass
 
You can use matt with epoxy but you have to work around it. Wet down the surface to be covered with epoxy resin. Slap on the matt then put cloth over it and wet the whole thing down. I've also done it laying cloth on a wet out board, putting the matt on top and quickly wetting it out by daubing the epoxy on then picking it up putting in place. Not as easy to work with as Polyester but it can be done. Stitched matt to cloth is by far the easiest to work with, however.

For repairs to the hull, epoxy is the only way. It just sticks to any substrate so much better.

minaret 23-04-2013 15:16

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by Exile (Post 1218193)
So if poly is preferred for the reasons cited -- most notably in the case of gelcoat deck repairs where epoxy may make it difficult for new gelcoat to adhere -- can anyone recommend a high-quality poly brand/system that is practical for both small jobs & stowage onboard?

I believe poly & vinylester fairing materials have been recommended by Minaret & others in other threads, but I'm not sure I caught any suggestions for resin & catalyst. Obviously, the quantities pros like Minaret use would not be realistic unless smaller containers are available.



Poly resin is generally either orthotropic or isotropic. You want the latter, Iso resin. There are many major suppliers and vast differences between products both with poly resin and catalyst, of which there are also many types.

I can currently only speak to west coast suppliers. I am currently using 55 gallon drums of ortho from Revchem for production volume work, and my favorite poly resin, Orca Composites P-17 Iso resin with 480 MEKP or Hi-Point 90, both in drums and by the fiver. Current supplier for most laminating process materials is Fiberlay. They are awesome, Dave even teaches classes for high end industrial processes. P-17 costs me about $200 a fiver, compared to $500 a fiver for WEST. It's great resin. I also get VE Infusion resin from them, and all sorts of other hard to source materials. Good website too, if you know what you're doing.

minaret 23-04-2013 15:24

Re: Epoxy vs Fiberglass
 
Quote:

Originally Posted by roverhi (Post 1218288)

For repairs to the hull, epoxy is the only way. It just sticks to any substrate so much better.


If you do repairs to the hull in epoxy, you are forced to finish in paint instead of doing a Gelcoat repair. Why turn a $200 repair into a $20k full paint job? Unless the boat is already painted instead of gelcoated, it makes no sense. Even then I'd only do it for very small repairs, as unless the boat is built in epoxy the dissimilar flex rates will cancel out the superior bonding when considering delam. A big epoxy repair will be much stiffer than the poly hull around it, creating stress risers right at the bond edge of the repair where you don't want it.


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